Pedantic compile with MSVC, GCC and Clang MinGW

[RaceTheMaSe]

An attempt to build bullet3 with more pedantic compile settings for x86-64 targets

Contains:

• A few bug fixes
• Style changes / corrections
• override specifier via BT_OVERRIDE macro to satisfy both C++98 and C++11 onwards

Tested compilers:

• MSVC 2019
• GCC 11.3
• Clang 14 MinGW
• Clang 17 MinGW

Tested compile settings:

• MSVC: /W4 and disable some
• GCC and Clang: -Wall -Wextra -Wpedantic and disable some
• both float and double precision

As it was stated that this project should be C++98 compatible, this was the primary setting, the other C++11.

Please note that the changes are only checked so it compiles. It still works in a project that uses rather basic features of this library, so not thoroughly tested.

Integrate / cherry-pick as much as you think fits.